Survival, growth and regeneration in explants of four temperate gorgonian species in the Mediterranean Sea

Abstract

During the last few decades, Mediterranean epibenthic assemblages have been involved in mass mortality events, in which sea fans were one of the most threatened groups. Explants of the most common Mediterranean gorgonians (Paramuricea clavata, Eunicella cavolinii, E. singularis, and E. verrucosa, 40 explants from each species) were transplanted in the field in order to evaluate the response to transplantation, survival and growth rate of the cuttings during an annual cycle, from February 2003 to March 2004. Colonies of each species overcame transplantation stress and during the first three months they showed a mean survival rate of 98% and an average positive growth rate of 7.65%. In the summer season 2003, during the heatwave that affected the Mediterranean basin, the experimental cuttings suffered, showing a mean negative growth rate and a reduction of survival. At the end of the stress event, P. clavata revealed the worst recovery while all Eunicella species showed a good ability to recover. In particular, E. singularis evidenced the highest resilience among the species. The transplant method described here could be employed to try to recover sea fan populations in the precoralligenous and coralligenous communities in possible future projects of restocking, where anthropic activities (anchoring and/or fishing) and global warming are deeply compromising their survival. Moreover, a species‐specific capability to recover was identified after the stress event concomitant to the increase of the sea temperature.